Community Response Research Articles

Dual stable isotopes approach reveals the nitrogen sources, transformations, and effects on phytoplankton community structure in a large floodplain lake

BackgroundAnthropogenic activities have led to increased N input and changes of N transformation processes in lake systems. However, changes in phytoplankton community structure caused by phytoplankton’s preference for N utilization under the increasing N input remain poorly understood. This study used nitrate isotopes (δ15N-NO3− and δ18O-NO3−) to investigate seasonal differences in N cycling as well as associated response of phytoplankton biomass and community composition.ResultsResults showed that the average δ15N-NO3− values in spring, summer, autumn, and winter were 7.6 ± 0.7‰, 6.1 ± 0.7‰, 5.5 ± 1.8‰, and 7.4 ± 1.2‰, respectively. Accordingly, the average δ18O-NO3− values showed the following order: winter (12.8 ± 1.0‰) > summer (11.5 ± 0.9‰) > spring (10.3 ± 0.9‰) > autumn (7.9 ± 1.7‰). The main nitrate sources in Lake Poyang were soil N, N fertilizer, and the manure and sewage in all seasons, contributing 93.8%, 3.3%, and 2.8%, respectively. Nitrification and algal-derived nitrate (NO3−-N) assimilation were the main biochemical processes affecting N. In spring, the signal of nitrification was stronger, while in autumn, the signals of N assimilation by algae were more pronounced. The phytoplankton community composition varied with the seasonal changes of N concentrations and forms. The total biomass of phytoplankton in winter was the lowest of all four seasons and it was negatively correlated with NO3−-N concentration (P < 0.05).ConclusionsThe results of this study contribute to a better understanding of the role of available forms of N in floodplain lake and provide essential support for prediction of phytoplankton growth and functions. Our work deciphers the role of phytoplankton in the lake N cycle, providing theoretical support to management of phytoplankton community to future environmental changes.

Compositional shifts and co-occurrence patterns of topsoil bacteria and micro-eukaryotes across a permafrost thaw gradient in alpine meadows of the Qilian Mountains, China.

Soil microorganisms play a pivotal role in the biogeochemical cycles of alpine meadow ecosystems, especially in the context of permafrost thaw. However, the mechanisms driving microbial community responses to environmental changes, such as variations in active layer thickness (ALT) of permafrost, remain poorly understood. This study utilized next-generation sequencing to explore the composition and co-occurrence patterns of soil microbial communities, focusing on bacteria and micro-eukaryotes along a permafrost thaw gradient. The results showed a decline in bacterial alpha diversity with increasing permafrost thaw, whereas micro-eukaryotic diversity exhibited an opposite trend. Although changes in microbial community composition were observed in permafrost and seasonally frozen soils, these shifts were not statistically significant. Bacterial communities exhibited a greater differentiation between frozen and seasonally frozen soils, a pattern not mirrored in eukaryotic communities. Linear discriminant analysis effect size analysis revealed a higher number of potential biomarkers in bacterial communities compared with micro-eukaryotes. Bacterial co-occurrence networks were more complex, with more nodes, edges, and positive linkages than those of micro-eukaryotes. Key factors such as soil texture, ALT, and bulk density significantly influenced bacterial community structures, particularly affecting the relative abundances of the Acidobacteria, Proteobacteria, and Actinobacteria phyla. In contrast, fungal communities (e.g., Nucletmycea, Rhizaria, Chloroplastida, and Discosea groups) were more affected by electrical conductivity, vegetation coverage, and ALT. This study highlights the distinct responses of soil bacteria and micro-eukaryotes to permafrost thaw, offering insights into microbial community stability under global climate change.IMPORTANCEThis study sheds light on how permafrost thaw affects microbial life in the soil, with broader implications for understanding climate change impacts. As permafrost degrades, it alters the types and numbers of microbes in the soil. These microbes play essential roles in environmental processes, such as nutrient cycling and greenhouse gas emissions. By observing shifts from bacteria-dominated to fungi-dominated communities as permafrost thaws, the study highlights potential changes in these processes. Importantly, this research suggests that the stability of microbial networks decreases with permafrost degradation, potentially disrupting the delicate balance of these ecosystems. The findings not only deepen our understanding of microbial responses to changing climates but also support the development of strategies to monitor and potentially mitigate the effects of climate change on fragile high-altitude ecosystems.

Response of Community Characteristics and Assembly Mechanisms of cbbL-Carrier Carbon-Fixing Microorganisms to Precipitation Changes in Alpine Lakeshore Wetland

Precipitation change strongly influences soil microbial communities, and precipitation patterns have become a key factor affecting carbon and nitrogen cycling processes in wetland ecosystems. The cbbL gene is a key gene in the fixation of carbon dioxide during the Calvin cycle. However, the response of cbbL-carrier carbon-fixing microorganisms in the lakeshore wetland to precipitation change remains unclear. To this end, we established 25% and 50% increased and decreased precipitation treatments, along with a natural control, and used high-throughput sequencing to investigate the response of the cbbL-carrier carbon-fixing microbial community in a lakeshore wetland of Qinghai Lake in response to precipitation change. The results showed that a 25% reduced precipitation treatment significantly increased the relative abundance of Chlorophyta and Bradyrhizobium. pH was found to be the most important factor influencing the carbon-fixing microbial community, with a significant positive correlation with Ferrithrix. A 25% increased precipitation treatment significantly increased the relative abundance of aerobic chemoheterotrophy and chemoheterotrophy, while a 25% reduced precipitation treatment significantly increased the relative abundance of nitrogen fixation. The increased precipitation and 50% reduced precipitation treatments shift the community assembly process of cbbL-carrier carbon-fixing microorganisms from randomness to determinism. Co-occurrence network analysis showed that the network complexity and connectivity between species of cbbL-carrier carbon-fixing microorganisms initially decreased and then increased with increasing precipitation. In summary, precipitation change tended to reduce the carbon sequestration potential of the lakeshore wetland, while a 25% reduced precipitation treatment favored the nitrogen fixation process in these wetlands.

Islam dan Demokrasi: Kajian Pemikiran Teologis dan Praktik Politik di Indonesia

Islam and democracy are often considered two concepts with fundamental differences, particularly in terms of sovereignty, law, and decision-making processes. However, in the context of Indonesia, these two concepts have interacted in a unique and dynamic way. As the largest democratic country with a Muslim majority, Indonesia serves as a social laboratory for testing the compatibility between Islam and democracy. This research examines the Muslim community's response to democracy through two main approaches: theological thinking rooted in Islamic values such as syura (consultation), ‘adalah (justice), and musawah (equality), as well as political practices reflected in Muslim participation in Indonesia's democratic system. Furthermore, this research explores the role of Islamic organizations such as Nahdlatul Ulama (NU) and Muhammadiyah in promoting inclusive democracy, as well as the challenges faced, such as radicalism and identity politics. The research findings indicate that Islam is not only compatible with democracy but also enriches democratic values through ethical and moral principles. Thus, this paper provides an important contribution to understanding the relationship between Islam and democracy, particularly in the Indonesian context.

Development, dissemination and community response towards the first community notice regarding misrepresented illicit anabolic-androgenic steroids in circulation in Australia.

Drug alerts aimed at both people who use drugs and health workers help to prevent acute harms from unpredictable illicit drug markets and by equipping health workers to handle unusual drug events and share vital information with service users. However, there has never been an alert produced for anabolic-androgenic steroids (AAS), an important class of illicit drugs. We report on the development, implementation and community receptivity of the first-ever AAS community drug alert. Based on findings from samples collected during the first month of an AAS checking trial conducted by drug checking service CheQpoint, we identified contamination in two oxandrolone samples, which prompted issuing of the first-ever AAS community notice. Drawing on digital ethnographic techniques, we collected and analysed social media comments on the notice to assess AAS community perceptions and the broader impact of this harm reduction initiative. The Instagram post by CheQpoint reached 1376 users, with 3429 impressions and 87 interactions. Community feedback indicated receptivity to the notice, with several people in the community recognising the prevalence of AAS adulteration. Responses highlighted the need for more thorough testing and indication of sample content, given the perception of a growing number of new people using AAS. This study, the first to describe a community notice for illicit market AAS, reveals a strong demand for harm reduction interventions. We call for the urgent expansion of drug-checking services to provision for AAS and, thus, provide equitable health support to address systemic gaps for this group.

Spatial and seasonal distribution of selected nitrogen cycle genes in deep waters of the Baltic Proper

Marine nitrogen cycle ultimately depends on the biological responses of oceanic microbial communities. It indirectly regulates primary production and influences the strength of the biological pump, which contributes to the oceanic uptake of atmospheric carbon dioxide (CO2). As the microbial community structure and functional capacities remain underestimated in terms of temporal and geographical coverage in the Baltic Sea, our understanding of the nitrogen cycle with respect to ecosystem functioning and climate change is limited. Therefore, in this study, we investigated the seasonal and spatial structure of microbial community abundance involved in the nitrogen loss (denitrification, anammox), reduction processes (dissimilatory nitrate reduction (DNR), dissimilatory nitrite reduction to ammonium (DNRA), and oxidation process (nitrification) in the Baltic Proper (Bornholm Deep, Gdańsk Deep, and Gotland Deep). Specifically, we focused on waters below the halocline at depths ranging from 75 to 135 m, characterized by changeable oxygen conditions. The potential of selected nitrogen processes was resolved by mapping raw reads against nitrogen cycle genes identified in de novo assembled metagenomes. Taxonomic analysis of bacterial and archaeal communities, based on paired-end raw reads, revealed that nitrification, DNR, and denitrification potential were primarily associated with the Nitrosopumilaceae and Thioglobaceae families within these phyla. Ammonia oxidation products likely fueled the production of nitrous oxide (N2O), with nitric oxide reductase (NOR)—an enzyme encoded by the Thioglobaceae genome—being responsible for further reduction. Anammox-related genes were not present within sites, thus denitrification pathway enzymes, namely, NOR and N2O reductase (NOS) were responsible for nitrogen loss. At all sites, genes encoding nitrogen reduction enzymes were most abundant, while the presence of NOS encoding genes was found in Bacteroidetes and Proteobacteria phyla within all sites. Our findings revealed no significant spatial variation, suggesting that the studied ecosystem exhibits a consistent nitrogen processing capacity across different locations. However, seasonality emerged as a key factor, as changes in nutrient and oxygen conditions throughout the year significantly influence microbial activity and the associated nitrogen-cycling processes.

Response of Soil Microbial Communities in Extreme Arid Deserts to Different Long-Term Management Methods

(1) Background: As population growth accelerates, unsustainable practices such as excessive cutting and burning of desert plants in the transition zones between deserts and oases have led to widespread vegetation loss. (2) Methods: The experiment was conducted in the oasis transition zone on the southern edge of the Taklamakan Desert from 2010 to 2023 year. Among the treatments included a control group (CK), cutting in spring (CS), cutting in fall (CF), burning in spring (BS), and flood water irrigation (FI). We used high-throughput sequencing to determine soil microbial composition and diversity and routine laboratory methods to determine soil physical and chemical properties and enzyme activities. (3) Results: No significant differences in bacterial alpha diversity (Chao1, Dominance, Observed_features, Pielou_e, Shannon, and Simpson) across the different long-term disturbance patterns. In fungi, the CK treatment showed significantly higher Chao1, Shannon, and Observed_features indices compared to BS and FI. Principal component analysis revealed a substantial reduction in bacterial community diversity in BS compared to FI, while fungal communities were lower in CK and CS compared to BS, CF, and FI; (4) Conclusions: Soil moisture content, electrical conductivity, organic carbon, and the activity of the enzyme cellobiohydrolase as key factors shaping the bacterial community. For fungi, organic carbon and the β-1,4-glucosidase enzyme were the main drivers.

Adaptive biodegradation and mechanism study of volatile chlorinated aromatic hydrocarbons in landfill cover soil bioreactor zone.

Landfill gases in the bioreactor zone of waste disposal sites have posed serious threats to human health and ecosystems. This work focuses on the bioreactor zone of landfill cover soil to investigate the adaptive biodegradation mechanism of volatile chlorinated aromatic hydrocarbons (CAHs). Through long-term operation of a bioreactor system, the degradation processes of various CAHs and the dynamic changes in microbial communities in the cover soil are systematically studied. The results indicate that microbial communities in the cover soil exhibit adaptive growth and metabolic characteristics in the presence of CAHs. The variations in dominant bacterial genera at different depths of the cover soil reveal the metabolic adaptability of microorganisms under different oxygen concentration conditions. In particular, the abundance changes of aerobic and anaerobic bacteria significantly influencing CAHs degradation. Correlation analysis reveals a close relationship between environmental factors such as oxygen concentration, CAHs concentration, chloride ion concentration, and the composition of microbial communities, highlighting the sensitive response of microbial communities to environmental factors. Furthermore, the study identifies inhibitory effects of high concentrations of certain CAHs on specific bacterial genera, implying the significance of complex competition and inhibition relationships during the degradation process. This study deeply elucidates the adaptive degradation mechanism of volatile chlorinated aromatic hydrocarbons by microbial communities in the cover soil, providing essential theoretical and practical guidance for pollution control in landfill sites.

Response of Soil Phage Communities and Prokaryote-Phage Interactions to Long-Term Drought.

Soil moisture is a fundamental factor affecting terrestrial ecosystem functions. In this study, microscopic enumeration and joint metaviromic and metagenomic sequencing were employed together to investigate the impact of prolonged drought on soil phage communities and their interactions with prokaryotes in a subtropical evergreen forest. Our findings revealed a marked reduction in the abundances of prokaryotic and viral-like particles, by 73.1% and 75.2%, respectively, and significantly altered the structure of prokaryotic and phage communities under drought. Meanwhile, drought substantially increased the fraction of prokaryotic communities containing lysogenic phages by 163%, as well as the proportion of temperate phages. Nonetheless, drought likely amplified negative prokaryote-phage interactions given the nearly doubled proportion of negative links in the prokaryote-phage co-occurrence network, as well as the higher frequency and diversity of antiphage defense systems found in prokaryotic genomes. Under drought, soil phages exerted greater top-down control on typical soil k-strategists including Acidobacteria and Chloroflexi. Moreover, phage-encoded auxiliary metabolic genes may impact host metabolism in biosynthesis-related functions. Collectively, the findings of this study underscore the profound impact of drought on soil phages and prokaryote-phage interactions. These results also emphasize the importance of managing soil moisture levels during soil amendment and microbiome manipulation to account for the influence of soil phages.

Cultivar-specific rhizosphere microbial community responses to cadmium-NaHCO3 stress in relation to cadmium accumulation in rice.

Understanding the response of rhizosphere microbial communities to cadmium (Cd)-alkali stress from a cultivar-specific perspective is important for regulating Cd accumulation in rice. Pot experiments were conducted using low-Cd-accumulating Y15 and high-Cd-accumulating Y40, by addition of 0.0 %, 0.3 %, and 0.6 % NaHCO3 (A0, A1, and A2, respectively) to Cd-contaminated (0.62 mg/kg) soil. The plant Cd and soil DTPA-Cd decreased significantly with increasing NaHCO3 dose for Y15, but not for Y40. Cd-NaHCO3 stress reduced the richness and evenness of rhizosphere microbial communities, especially in A1 of Y15 and A2 of Y40. The Y15 rhizosphere shifted from the equal abundance of Proteobacteria and Firmicutes under A0 to the predominance of Proteobacteria and enriched with growth-promoting Alphaproteobacteria (Roseomonas, Brevundimonas), Cd-fixating Firmicute (Bacillus), and nitrogen-cycling Bdellovibrionota (Peredibacter) under A1 and A2. The Y40 rhizosphere contained comparable Proteobacteria and Firmicutes under A0 and A1; under A2, it was dominated by Proteobacteria and enriched with Cd-activating Bacteroidota (Barnesiella, Taibaiella), lignin-degrading Chloroflexi (Anaerolinea), and Cd-fixating or growth-promoting Gammaproteobacteria (Lysobacter, Pseudomonadales, Acinetobacter). The Y40 and Y15 rhizosphere exhibited laziness in multiple FAPROTAX functions, and were activated in 11 and 18 KGEE pathways including amino acid metabolism in A2 and A1, respectively. The results provide new insights into Cd-alkali tolerance in rice.

Diverse adaptation strategies of generalists and specialists to metal and salinity stress in the coastal sediments.

Understanding the distinct roles and responses of bacterial community to environmental stressors is crucial for effective ecosystem management and conservation. Despite this, there is limited research on how environmental gradients specifically impact generalist and specialist subcommunities. This study investigates these subcommunities in the sediments of Jinzhou Bay, highlighting their distinct responses to environmental gradients. Generalists thrive in disturbed environments due to their broad ecological tolerances, while specialists show higher diversity in the stable, less contaminated upstream areas. At the genus level, Porphyrobacter and Subgroup_23 were identified as the dominant taxa of generalists, while Woeseia and Lutibacter were the dominant species of specialists. Physicochemical parameters, especially metals and salinity, significantly influence subcommunity composition. Generalists are adaptable to a wider range of factors, whereas specialists are affected by specific parameters, reflecting their narrower niches. The generalists exhibit a greater abundance of salinity tolerance genes compared to the specialists; however, this trend does not extend to metal resistance genes. Keystone taxa, primarily specialists, play crucial roles in maintaining community stability. Our results underscore the importance of considering both generalists and specialists in ecological assessments, offering insights for the management and conservation of bacterial microbial diversity in coastal ecosystems.

Life history: Exploring the lives of women living with HIV and disability in vulnerable contexts regarding their food security

abstract Multiple disadvantages can heighten the risk of food insecurity for people. Unfortunately, when we do not interrogate the cycles that arise, they remain poorly understood and, thus, inadequately addressed. Through life history methodology, we investigated the lives of two women living with human immunodeficiency virus (HIV) and disability to obtain a deeper understanding of their food security. The researchers were intermittently embedded within the community over four years and experienced many key events with the households. During this time, the lives of these women changed significantly, both because of the voluntary community intervention provided, and the shocks and stressors that impacted their lives. Three important themes developed in the analysis. Firstly, the women displayed resilience, which contributed to their food security. Notably, both women did not view their disabilities as disabling. Secondly, systemic failures not only limited food access but also compounded these women's food insecurity. Thirdly, the international measures taken to derive population statistics of food and nutrition security (FNS) can be wholly inadequate or incorrect. This can lead to traditional food security programmes not providing a sustainable solution. Therefore, statistical information needs to be supplemented by lived realities to ensure that the community and policy response can make a meaningful difference.

Professionals' Readiness to Manage Violence Against Women.

Over recent years, community-based responses to domestic violence against women have become an important topic, and there is growing recognition that domestic violence requires a comprehensive response from agencies across a variety of community sectors. When reaching out for help, female survivors of domestic violence need to have access to a broad range of services, empowering professionals to manage violence against women, and coordinated community responses that promote safety, autonomy, and integration. Since the early 1990s, Portugal has been gradually moving toward a community-based approach to domestic violence against women where local organizations and professionals are major stakeholders of this policy. Besides having had an increased network of services implemented, it is important to examine how prepared service providers are to respond effectively. The current study analyzed how ready professionals in Portugal are to deliver interventions targeting violence against women. A total of 585 professionals from different backgrounds completed a readiness survey. The results revealed that, despite their perceived readiness, professionals are not duly prepared to respond effectively to violence against women. They lack the appropriate knowledge and training to respond effectively to survivors. Hence, further efforts must be made to change professional practices and services to ensure that abuse is recognized, barriers are overcome, and interventions are more effective.

Invisible Threads: Emerging Water Governance in the Multi‐Actor Dynamics of the Mira‐Mataje Transboundary River Basin

ABSTRACTIn recent years, scholarly interest has surged in exploring the emergence of new governance regimes that redefine the self‐governing capacities of local communities in water management, navigating security challenges to ensure compliance to central government water laws and regulations. Embracing polycentric governance across various levels of political interaction provides insights into the factors driving the establishment of these regimes, particularly in regions with limited state presence, and where the threat of climate impact has become visible by climate extreme events as drought. This approach emphasizes the importance of decentralized, collaborative systems for effectively and sustainably managing water resources. Such systems promote equitable water use, regional stability, and resilience to drought through innovative, community‐driven solutions aimed at addressing water scarcity challenges. While the former, polycentric governance, involves multiple centers of authority making decisions collaboratively, the latter, decentralized governance, refers to communities independently managing their affairs. To understand evidence related to these dynamics, we focus on actors' interactions around the downstream area of the transboundary Mira River Basin, between Ecuador and Colombia. Employing mixed method approaches such as qualitative interviews, policy analysis, and participatory observation provides comprehensive insights into the complex interactions shaping transboundary water governance and community responses. These methods facilitate a thorough understanding of how institutional arrangements and governance structures evolve and adapt in diverse sociopolitical contexts, offering valuable lessons for sustainable water management strategies on (local) scale or on (cross‐border) collaboration. This is particularly crucial in addressing the challenges posed by drought scenarios, ensuring resilience and adaptability in water governance worldwide.

Responsible AI in biotechnology: balancing discovery, innovation and biosecurity risks

The integration of artificial intelligence (AI) in protein design presents unparalleled opportunities for innovation in bioengineering and biotechnology. However, it also raises significant biosecurity concerns. This review examines the changing landscape of bioweapon risks, the dual-use potential of AI-driven bioengineering tools, and the necessary safeguards to prevent misuse while fostering innovation. It highlights emerging policy frameworks, technical safeguards, and community responses aimed at mitigating risks and enabling responsible development and application of AI in protein design.

Idealism and ambiguity: encountering professional socialization in an emerging profession

ABSTRACT This collaborative autoethnography explores the professional socialization experiences of three former primary-role academic advisors within the context of academic advising as an emerging profession. Two main themes emerged from the collaborative dialogue and analysis: 1) the tension between individual professional identity and the identity of organizations in an emerging field, characterized by ambiguity and idealism; and 2) the role of reflection in gaining conscious awareness and navigating this tension. The study highlights the potential of reflective practice in shaping professional identity, managing transitions, and fostering critical self-awareness and empowerment. Engaging in reflective practices allows advisors to bridge personal beliefs with professional ethics, cultivate a sense of community and cultural responsiveness, and develop a more coherent and authentic professional identity. The findings emphasize the importance of integrating reflective practice into professional development programs to support advisors in navigating the complexities of their roles and adapting to evolving professional landscapes. Institutions are encouraged to facilitate reflective practice through structured opportunities, supervision, and peer discussions to promote continuous growth and excellence in academic advising.

Warming alters plankton body-size distributions in a large field experiment

The threat of climate change has renewed interest in the responses of communities and ecosystems to warming, with changes in size spectra expected to signify fundamental shifts in the structure and dynamics of these multispecies systems. While substantial empirical evidence has accumulated in recent years on such changes, we still lack general insights due to a limited coverage of warming scenarios that span spatial and temporal scales of relevance to natural systems. We addressed this gap by conducting an extensive freshwater mesocosm experiment across 36 large field mesocosms exposed to intergenerational warming treatments of up to +8 °C above ambient levels. We found a nonlinear decrease in the overall mean body size of zooplankton with warming, with a 57% reduction at +8 °C. This pattern was broadly consistent over two tested seasons and major taxonomic groups. We also detected some breakpoints in the community-level size-temperature relationship, indicating that the system’s response shifts noticeably above a certain level of warming. These results underscore the need to capture intergenerational responses to large gradients in warming at appropriate scales in time and space in order to better understand the effects of warming on natural communities and ecosystems.

Nitrogen metabolic responses of non-rhizosphere and rhizosphere microbial communities in constructed wetlands under nanoplastics disturbance

Constructed wetlands (CWs) serve as crucial sinks for nanoplastics, making them a significant research hotspot regarding the impacts of nanoplastics on the nitrogen metabolism within microbial communities. However, there has been a lack of comparative analysis between rhizosphere and non-rhizosphere microbial communities under nanoplastics disturbance. This study analyzes the nitrogen metabolic responses of these microbial communities in CWs following repeated nanoplastics disturbance. Results indicated that repeated nanoplastics disturbances led to a 17.72% decrease in the relative abundance of nitrifying bacteria in rhizosphere microbial community, while the relative abundance of Polaromonas increased by 5.24% in non-rhizosphere community. Microbial network revealed that rhizosphere microbial community primarily contributed to nitrogen metabolism by forming a tightly connected network. In contrast, non-rhizosphere microbes dominated nitrogen cycling by promoting energy and information exchange among microbes. Furthermore, rhizosphere and non-rhizosphere microbial communities exhibited distinct resistance and adaptation to nanoplastics disturbance. Rhizosphere microbes responded by activating antioxidant systems, whereas non-rhizosphere microbes could develop adaptive growth and metabolism, using nanoplastics as a carbon source. The adaptation strategies of non-rhizosphere community proved more advantageous for coping with persistent nanoplastics disturbance. This study comprehensively investigated the differences of nitrogen metabolism between rhizosphere and non-rhizosphere microorganisms in CWs under nanoplastics disturbance.

Pre-exposure to stress reduces loss of community and genetic diversity following severe environmental disturbance.

Environmental stress caused by anthropogenic impacts is increasing worldwide. Understanding the ecological and evolutionary consequences for biodiversity will be crucial for our ability to respond effectively. Historical exposure to environmental stress is expected to select for resistant species, shifting community composition toward more stress-tolerant taxa. Concurrent with this species sorting process, genotypes within resistant taxa that have the highest relative fitness under severe stress are expected to increase in frequency, leading to evolutionary adaptation. However, empirical demonstrations of these dual ecological and evolutionary processes in natural communities are rare. Here, we provide evidence for simultaneous species sorting and evolutionary adaptation across multiple species within a natural freshwater bacterial community. Using a two-phase stressor experimental design (acidification pre-exposure followed by severe acidification) in aquatic mesocosms, we show that pre-exposed communities were more resistant than naive communities to taxonomic loss when faced with severe acid stress. However, after sustained severe acidification, taxonomic richness of both pre-exposed and naive communities eventually converged. All communities experiencing severe acidification became dominated by an acidophilic bacterium, Acidiphilium rubrum, but this species retained greater genetic diversity and followed distinct evolutionary trajectories in pre-exposed relative to naive communities. These patterns were shared across other acidophilic species, providing repeated evidence for the impact of pre-exposure on evolutionary outcomes despite the convergence of community profiles. Our results underscore the need to consider both ecological and evolutionary processes to accurately predict the responses of natural communities to environmental change.

"Assessment of potential eutrophication in coastal waters of Gran Canaria: Impact on plankton community under CO2 depletion".

Population growth in coastal tourist areas is leading to enhanced waste production, raising concerns about potential nutrient release increases and the resulting impact on marine ecosystems through eutrophication. Knowledge of the specific impacts of eutrophication on plankton communities in many of these regions is limited, highlighting the need for further research and appropriate environmental management strategies. To help address these gaps, we conducted a 30-day mesocosm study in the coastal waters of Gran Canaria, Canary Islands, a major European tourist destination, and the third most densely populated autonomous community in Spain. With the aim of assessing the effects of nutrient input on biomass, primary production (PP) and recycling processes by phytoplankton, zooplankton, and bacterioplankton, we simulated three nutrient discharge intensities (Low, Medium, and High), with daily additions of 0.1, 1, and 10μmolL-1 of nitrate, respectively, along with phosphate and silicate. We observed that PP, chlorophyll a (Chl-a), and biomass increased linearly with nutrient input, except in the High treatment, where CO2 depletion (<1.0μmolL-1) and an alkalinity increase (>2500μmolL-1) resulted in reduced PP. Despite limitations in nitrogen (Control, Low, and Medium) or carbon (High) availability across treatments, which led to stabilized or decreased PP rates and dissolved organic carbon (DOC) concentrations, bacterial degradation remained active in all treatments. This microbial activity resulted in an accumulation of recalcitrant chromophoric dissolved organic matter (CDOM), indicating the resilience of carbon recycling processes under varying nutrient conditions. Furthermore, a clear succession was evident in all enriched treatments, transitioning from an oligotrophic condition dominated by pico- and nanophytoplankton to a eutrophic state primarily composed of diatoms. However, under CO2 depletion, diatoms experienced a decline in the High treatment, leading to the proliferation of potentially mixotrophic dinoflagellates. Microzooplankton was less sensitive than mesozooplankton to the decrease in prey availability and high pH caused by CO2 depletion. Interestingly, the Medium treatment showed high efficiency in terms of PP, despite reaching CO2 levels near of 1.0μmolL-1 by the end of the experiment. PP rates increased from 10 to 100μgC·L-1·d-1 during the first week and remained stable as diatoms predominated throughout the study period. These findings provide valuable insights into the responses of plankton communities to varying nutrient inputs and emphasize the importance of considering the effects of DIC depletion, along with changes in total alkalinity, in eutrophication scenarios as well as in ocean alkalinity enhancement experiments aimed at reducing carbon dioxide emissions.